1. Field of the Invention
The present invention relates generally to methods and apparatus for the removal by oxidation of trace contaminants from air and oxygen atmospheres.
2. Description of the Prior Art
In the closed atmosphere of a spacecraft or submarine, trace contaminants can reach toxic concentrations. These air pollutants range from metabolic products such as alcohols, esters, hydrogen sulfide and ammonia to solvents such as Freons, aromatics, alcohols, and ketones which are adsorbed or dissolved in equipment and lubricants. Further, there is a need to eliminate trace contaminants in the zero air used for the standardization of air monitoring equipment.
In the past, these contaminants have been controlled by adsorption, absorption and catalytic oxidation. That technology has many severe shortcomings. The adsorbents and absorbents become exhausted with use and many of them are suitable for only a particular class of compounds. Regenerative systems tend to be complicated and weighty. Catalysts are restricted in use, require heating, may generate toxic products, and can be poisoned. To date, activated charcoal adsorption has been most widely used for contaminant control in spacecraft, but this material suffers from the above shortcomings and has a very low capacity for many classes of compounds.
There is extensive literature on the production of a multitude of chemicals in various kinds of electrical discharges. However, only a few authors have suggested that these discharges might be used to treat or remove pollutants or contaminants. The literature which does consider the removal of contaminants emphasizes the energy efficiency of removal and quantity of material that can be efficaciously treated. No attempt is known to specifically remove small amounts of material, nor is any reported data known that show that the efficiency of removal does not significantly decrease with decreasing concentration of contaminant.